Do not transplant outside until night time temperatures are steadily 10°C (50°F) or warmer. This may mean keeping seedlings indoors for up to a month. The plants should not require any fertilizer until transplant time.
Tomatoes thrive in fertile, well-drained soil that is high in organic matter. Dig in finished compost and/or manure, and add 1 cup complete organic fertilizer beneath each transplant. Dig a hole in the garden approximately the same size as the seedling container, or a couple of inches deeper. Invert the seedling and gently tease it from its container by holding the stem and supporting the root ball. Tomato seedlings can be transplanted either to the same depth of their container, or slightly deeper, up to the first set of leaves. Press the root ball into the soil, fill in with soil, and water thoroughly.